[Maxima] Operations on inf

[Raymond Toy]

Currently, maxima does interesting things like 4*inf -> 4*inf, inf/inf
-> 1, etc.

I have hacked on this a bit and maxima now says:

4*inf -> inf     
-1*inf -> minf   (debatable?)
inf/inf -> und   (or ind?)
inf*inf -> inf
inf*0 -> und     (or ind?)
(1-sqrt(2))*inf -> minf
(1+sqrt(2))*inf -> inf

But inf^2 -> inf^2, still, and x*inf -> x*inf.  I wasn't sure what to
do with x*inf, so I thought it best to leave it alone.

I'm sure there are other cases to consider.

Is this the direction we want Maxima to go in?

Ray